Due to the enactment of various safety laws, persons working at elevated positions, e.g., when washing the upper story windows of a building, etc., are required to be protected against falls. One common approach to achieve that end is the use of a safety belt which is worn on the worker's waist or a harness worn on the worker's torso. The belt/harness typically includes a D-ring or some other metal loop fixedly mounted on it. The D-ring is arranged to be connected, via a lanyard, to a "rope grab" device which is mounted on a safety line. The safety line typically comprises a rope, cable or other type of strong line which extends vertically from a fixed elevated anchor point downward past the point at which the worker is located. In fact in many applications the line extends all the way to the ground. The rope grab is arranged to slide along the safety line to follow the worker up or down the structure on which the worker is working. In the event that the worker should fall off of the structure the rapid downward pull on the rope grab caused by the momentum of the worker causes the rope grab to automatically immediately engage and lock itself into a fixed position on the safety line, thereby arresting the worker's fall and supporting him/her until he/she can be rescued.
Heretofore, some prior art lanyards for connecting the worker's safety belt or harness to the rope grab or to a fixed anchor point in safety systems have included some means to indicate that the lanyard has been stressed by a fall. For example, in U.S. Pat. No. 4,253,54 (Dalmaso) there is disclosed a lanyard which when stressed by a fall results in the breakage of stitching and the release of a flag to indicate that occurrence. In U.S. Pat. Nos. 2,613,865 (Rose); 3,444,957 (Ervin, Jr.); 3,804,698 (Kinloch); 4,446,944 (Forrest et al.); and 4,538,702 (Wolner) there are disclosed shock absorbing safety belts or lanyards which include looped portions which are extended when the device is stressed, such as occurs when arresting a fall.
Other devices have been described in the patent literature for indicating the existence of stress on a member. For example U.S. Pat. No. 3,025,995 (Koelsch et al) discloses a container or case having deformable corners to indicate the absorption of a shock thereto. U.S. Pat. Nos. 2,294,897 (Ellis); 2,428,559 (Ellis); and 3,801,340 (Ellis) disclose adherent brittle films used on rigid articles which crack at predetermined strain levels to indicate stress on the articles.
Some safety harnesses or belts which are commercially available have made use of fibers of a contrasting color or appearance woven into the body of the strap(s) making up the harness or belt. These fibers are not visible if the harness or belt is intact, but become visible if the harness or strap should become worn away, such as by abrasion. If such fibers become visible that indicates that the harness/belt should be replaced or refurbished.
Notwithstanding the above, the prior art has not addressed the problem of providing some indication on a safety harness or safety belt that it has been subjected to a shock caused by the operation of a rope grab or other fall prevention device connected to the belt or harness having arrested the fall of a worker wearing the belt or harness so that the belt or harness can be checked and refurbished or discarded. Thus, a need exists for such a safety harness or belt.